Representation of Atoms (GCSE Physics)

Representation of Atoms

Nucleon vs Nuclide

A nucleon is a particle found in the nucleus, which would be either a proton or neutron.

A nuclide describes a nucleus characterised by the number of protons and neutrons.

Representing Atoms

We can represent atoms of an element in a very simple way. Let’s look at this example, involving Sodium.

1. We have represented the element Sodium using its symbol,’Na’.
2. The top number is the mass number. As previously mentioned, the mass number represents the protons and neutrons in an atom. Sodium has a mass number of 23.
3. The bottom number is the atomic number. As previously mentioned, the atomic number represents the protons in an atom. Sodium has an atomic number of 11.

Using the representation of an atom, we can work out exactly how many protons, neutrons and electrons it has.

• To work out protons: Simply look at the atomic number. This is the number of protons.
• To work out electrons: Simply look at the atomic number. We know that the number of protons is equal to the number of electrons.
• To work out neutrons: Use the ‘mass number – atomic number’. The mass number is the protons and neutrons, whilst the atomic number is just the protons. By taking atomic number away from mass number, we can find the number of neutrons.